karlgluck

What's this all about?

Digital cryptography! This is a subject I've been interested in since taking a class with Prof. Fred Schneider back in college. Articles pop up on Hacker News fairly often that pique my interest and this technique is the result of one of them.

Specifically, this is about Lamport signatures. There are many signature algorithms (ECDSA and RSA are the most commonly used) but Lamport signatures are unique because they are formed using a hash function. Many cryptographers believe that this makes them resistant to attacks made possible by quantum computers.

How does a Lamport Signature work?

karlgluck

learn Unreal Engine 5 (UE5 https://www.unrealengine.com) - free pro software, this is what the industry uses now
get it from the Epic Games Launcher https://store.epicgames.com/
do projects alone at first. take time to learn the basics. multiplayer is always more complicated.
buying asset store projects is an unreasonably effective way to learn https://www.unrealengine.com/marketplace
learning projects should be simple enough to finish. 
blueprints is a programming language for games used by UE5. Many games are possible using only blueprints code. start by searching for “beginner blueprint tutorials ue5”
find a good place to ask questions, like a Discord community or https://forums.unrealengine.com/

karlgluck

Vec3 Magnitude

These C# implementations of approximate magnitude with no square roots are actually slower than calling a native implementation in Unity, but if this were implemented intelligently in C there's a good chance they would be faster. In any case, they're here because it was a pain to get the magic numbers.

Accurate to within 4.5%.

public static float MagnitudeFast (this Vector2 self)
    {

karlgluck

# This will register a new job that removes itself from Get-ScheduledJob when finished

$Trigger = New-JobTrigger -Once -At (Get-Date).AddSeconds(3)
$TaskName = "SelfDestructingJob"
Register-ScheduledJob -Trigger $Trigger -Name $TaskName `
    -ScriptBlock ([scriptblock]::Create(@"
      ("Started job at " + (Get-Date) + ", waiting...") | Out-File -FilePath 'C:\ProofThatItWorks.txt'
      Start-Sleep 3
      ("Finished at " + (Get-Date)) | Out-File -Append -FilePath 'C:\ProofThatItWorks.txt'
      Unregister-ScheduledJob -Name '$TaskName' -Force

karlgluck

$Trigger = New-JobTrigger -Once -At (get-date).AddSeconds(5)
$JobOptions = New-ScheduledJobOption -StartIfOnBattery -RunElevated
$Job = Register-ScheduledJob -Name "TaskName" -Trigger $Trigger -ScheduledJobOption $JobOptions `
  -ScriptBlock {
    Sleep 5
  }

# From https://docs.microsoft.com/en-us/windows/win32/taskschd/task-scheduler-error-and-success-constants?redirectedfrom=MSDN
Set-Variable -Name "SCHED_S_TASK_HAS_NOT_RUN" -Value 0x00041303 -Option Constant

karlgluck

$JobName = "RunAtLoginExample"
$Enabled = $True # set to $False and run to remove the job

# https://stackoverflow.com/questions/40569045/register-scheduledjob-as-the-system-account-without-having-to-pass-in-credentia
# Output: %LOCALAPPDATA%\Microsoft\Windows\PowerShell\ScheduledJobs\$JobName
$accountId = ((Get-WMIObject -class Win32_ComputerSystem | Select-Object -ExpandProperty username)) 
$Trigger = New-JobTrigger -AtLogOn
$JobOptions = New-ScheduledJobOption -StartIfOnBattery -RunElevated

karlgluck

if (-not (Test-Path $Path)) { New-Item $Path -ItemType Directory | Out-Null }

karlgluck

$ZipFilePath = ""
$FileNameInZip = ""

Add-Type -AssemblyName System.IO.Compression.FileSystem
$Zip = [System.IO.Compression.ZipFile]::OpenRead($ZipFilePath)
$Zip.Entries | 
  Where-Object { $_.Name -eq $FileNameInZip } |
  ForEach-Object {
    [System.IO.Compression.ZipFileExtensions]::ExtractToFile($_, $_.Name, $true)

karlgluck

# Fill these in with your own values
$Username = "your_username"
$Branch = "main"
$PathToFile = "README.md"

# Go to [https://github.com/settings/tokens] and add a Personal Access Token with two scopes: "repo" and "read:org"
$GitHubAuthToken = "ghp_XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"

Invoke-WebRequest -Method Get -Uri "https://raw.githubusercontent.com/$Username/$Repository/$Branch/$PathToFile" -Headers @{Authorization="token $GitHubAuthToken"; 'Cache-Control'='no-cache'} | ForEach-Object { $_.Content } | Write-Host

karlgluck

void demoExtractBackBufferPixels(LPDIRECT3DDEVICE9 d3d_device) {
  
  // TODO: In your app, add FAILED() macros to check the HRESULTs passed back
  //       by each of the API calls. I leave these out for clarity.
  
  // Grab the backbuffer from the Direct3D device
  LPDIRECT3DSURFACE9 back_buffer = NULL;
  d3d_device->GetBackBuffer(0, 0, D3DBACKBUFFER_TYPE_MONO, &back_buffer);
  
  // Get the buffer's description and make an offscreen surface in system memory.